-----Original Message----- From: Jolley, Leonard - Beltsville, MD Sent: Thu 1/25/2007 12:36 PM To: William Adair Cc: Subject: RE: Ecological Sites vs. Ecological Systems Hello Susan and Bill, The USDA NRCS ecological site description concept is quite distinct and different from the Natureserve product. Ecological site descriptions are developed in conjunction with the National soil survey program. Ecological sites have their roots in the 'range site' concept, and range sites did owe a great deal to the vision of rangeland ecology articulated by Dyksterhuis in his 1949 and subsequent papers. Two papers that better describe the current rationale for ecological sites are: Stringham et al. March 2003. State and Transition modeling: An ecological process approach. J. Range Management 56:106-113 Bestelmeyer et al. March 2003. Development and use of state and transition models for rangelands. J. Range Management 56: 114-126. Ecological sites are defined as:
"A distinctive kind of land with specific physical characteristics that differs from other kinds of land in its ability to produce a distinctive kind and amount of vegetation." Brandon Bestelmeyer with USDA ARS at the Jornada Experimental Range has pointed out (in a personal communication): "Ecological Systems (ES) are sort of an ad hoc level in the NVC hierarchy that was produced for mapping, attempts to map plant associations led to too much inaccuracy, so the classes mapped were broadened. Ecological Site Descriptions (ESDs) are climo-edaphic units of land that may support a range of plant communities embedded within several alternative states that differ in ecosystem functions (e.g., nutrient cycling, hydrology). The biggest difference is that ecological system constructs are based on existing vegetation rather than potential vegetation and ecological systems are very broad. In our experience in the Chihuahuan Desert, ecological system systems classes describe gross vegetation structure (such as semidesert grassland or shrubland) that 1) homogenize/ignore important differences in vegetation structure from a management perspective (e.g., pristine grasslands and shrub invaded/at risk states within a âsemidesert grasslandâ ES) and 2) include both historical shrublands as well as shrublands representing degraded, former grasslands in the same ES class. So the crosswalk between ES and ESD classes is that ES classes MAY represent classes of communities, combinations of communities, alternative vegetation states, or combinations of alternative states occurring within one or more ESD classes, depending on how ES classes were defined in an area. In my opinion, ES classes are great for visualizing gross vegetation structure variation at a regional to national scale, but the vegetation state and community classes in ESDs represent potential and functional attributes and are more useful for scenario-building, assessment, and the generation of monitoring designs and monitoring hypotheses at landscape scales." I hope this is of help. Thanks, Leonard Jolley Ph.D. Rangeland Ecologist Resource Inventory and Assessment Division USDA Natural Resources Conservation Service Beltsville, MD 20705 (301) 504-2344 -----Original Message----- From: Ecological Society of America: grants, jobs, news on behalf of William Adair Sent: Wed 1/24/2007 7:05 PM To: ECOLOG-L@LISTSERV.UMD.EDU Cc: Subject: Re: Ecological Sites vs. Ecological Systems Hello Susan, The two approaches were developed separately and somewhat independently, and (to my knowledge) there is no explicit hierarchy linking the two. I'm not aware of any formal (or "official") methods that have been proposed for translating Ecological Sites into Ecological Systems, or vice versa. ------ The NRCS Ecological Sites concept is very site-specific. I have been told that this manuscript provides the foundation for the NRCS Ecological Sites concept: DYKSTERHUIS, E.J. - Condition and management of rangeland based on quantitative ecology. J. Range Mgmt., 1949, 2: 104-115. Personally, I've found that every range conservationist seems to have his/her own idea of what the term "Ecological Sites" means. The Grazing Lands Technology Institute's "Interpreting Indicators of Rangeland Health" is probably the best place to go to see how the NRCS Ecological Sites concept is (supposed to be) applied: http://www.glti.nrcs.usda.gov/ ------ In contrast, NatureServe developed the Ecological Systems concept as an intermediate level in the Federal Geographic Data Committee (FGDC) National Vegetation Classification System (NVC) hierarchy. This development was in part inspired by problems that arose when folks (like our lab) tried to map NVC Alliances and Associations across broad regions with remote sensing data. You can access the document that describes the Ecological System concept here: http://www.natureserve.org/publications/usEcologicalsystems.jsp ------ For a good general overview of vegetation and land cover classification concepts, I encourage you to check out the material on the ESA Panel on Vegetation Classification's web page: http://www.esa.org/vegweb/ Please note that the NVC standard is likely to change soon. This document summarizes some of the proposed changes: http://www.esapubs.org/bulletin/current/webpdfs_jan07/other1.pdf The draft mentioned on that website is located here: http://www.bio.unc.edu/faculty/peet/lab/temp/FGDCDraftStd_Aug2006.pdf Hope this helps... happy trails bill adair Utah State University Remote Sensing / GIS Laboratories Chaos is not just a theory -- it's a way of life -----Original Message----- From: Ecological Society of America: grants, jobs, news [mailto:[EMAIL PROTECTED] On Behalf Of =?iso-8859-1?Q?Susan_Geer?= Sent: Wednesday, January 24, 2007 3:22 PM To: ECOLOG-L@LISTSERV.UMD.EDU Subject: Ecological Sites vs. Ecological Systems What is the relationship of the "Ecological Site", a term used by the NRCS and BLM that is based on soil maps but includes vegetation characteristics to the "Ecological System", a term used by Natureserve? Is there a hierarchy, and can one be converted to the other? Thanks.